In an ultrasound-based structural health monitoring system, the minimum detectable damage size is directly related to the geometry of the sensor network and the structure. A higher sensor density may enable detection of smaller sized damages. Placing sensors on a structure, where the sensors may be ultrasonic or acoustic wave transducers capable of both transmitting and receiving elastic wave signals, requires taking into account the shape of the structure, location and shape of stiffeners, ribs, cutouts and other forbidden zones where sensors may not or cannot be placed, propagation characteristics of the structural material, and characteristics of the sensors. Often, the sensor placement process may be ad hoc, and does not optimize the probability of detection of damage with the smallest possible critical damage size. Conventional approaches may result in an excessive number of sensors and consequent redundancy of information, higher signal processing demands, as well as greater material and computational cost. There is a need, therefore, for an automated method for designing the optimal placement of sensors on a structure to ensure reliable damage detection of the smallest possible sized damage.